We take our journey out of Africa for granted, but scientists have long wondered how early humans found a way through the greatest desert on Earth. In the second episode of his Great Human Odyssey series, anthropologist Niobe Thompson brings us inside new discoveries that finally explain this incredible achievement and prove our ancestors did it twice as early as scientists thought possible. Next, we discover how humans survived the journey onwards, into a world completely foreign. How did they survive new diseases and adapt to environments from the tropics of East Asia to the Arctic? And what happened when our ancestors met Neanderthals?